Pivot angle motors of this category having corresponding break-out couplings serve the control of hydraulic pilot valves and thus represent the heart of so-called “direct drive” valves. Such direct drive valves control the position of one or more hydraulic control slide valves, i.e., without hydraulic reinforcement, by a regulated electric current. In some approaches, a fixed, invariable number of motors is provided and coupled to one another on one axle for such applications in this respect. The construction design of the overall motor or of the whole motor arrangement is in this respect may be driven and determined by the selected redundancy concept and may be designed and optimized individually in each case for this concept or for its exact number of motors. It is not easily possible to vary a selected redundancy concept with respect to the number of motors. Prior approaches may not account for the individual position measurement of the motor elements or of the individual motors, and thus there may not be a possibility of electronic monitoring of the smooth running and controlled movement of individual motor stator parts.
It is the object of the present disclosure to provide an improved motor arrangement for controlling pilot valves which can be varied more flexibly with respect to the number of motors used and with which a simplified individual position measurement of the motors is possible.
This object is achieved in accordance with the present disclosure by a motor arrangement for controlling pilot valves comprising at least three motors, the motors comprising at least one stator each and at least one rotor each, wherein the motors are provided at a common rotating shaft, with each motor being coupled to the rotating shaft via at least one respective mechanical coupling.
In this way, a modular cascadable arrangement of motors is provided which can be identical motors which are attachable in a redundant manner to a common shaft and which in this respect can be provided in different numbers without further construction modifications of the arrangement. In one example, the motor arrangement comprises at least three motors. In other embodiments, there is a threefold, fourfold, or sixfold redundancy of the motors. The redundant motor elements which comprise at least one stator each and at least one rotor each can in this respect be attached behind one another in an axial direction on a common rotating shaft.
In one example at least one respective electrical position sensor is provided at each motor.
It is advantageously possible with the aid of the position sensor to measure the current angle of deflection of the associated motor or motor element. For example, this sensor can serve both the exact regulation of the angular position and the monitoring of the movement of the motor or of the motor element.
In one example the coupling comprises at least one outer coupling part, at least one inner coupling part and at least one yoke spring arrangement, wherein the yoke spring couples the outer coupling part and the inner coupling part in normal operation of the corresponding motor and decouples them from one another in an improper operation.
In this way, the connection between the rotor and the rotating shaft is thus advantageously not rigid, but rather implemented via the mechanical coupling. The rotating shaft can thereby be moved onward while applying a defined break-out force in the event of a jamming of the stator and of the associated rotor, which corresponds to an improper operation of the corresponding motor. In this respect, the term normal operation of the motor means that operation in which no jamming or case of jamming is present between the stator and the rotor. With a redundant arrangement of at least three motors or motor elements, individual, jamming rotor segments can thus be pressed over by the other, non jamming motors in the sense of a majority decision.
In one example the rotor may be coupled to the outer coupling part by means of pins and by means of at least one ring. An advantageously simple coupling of the named components is hereby made possible.
In a further example two couplings may be provided between at least two motors. A coupling can in this respect be associated with the respective adjacent motor, with the couplings and the motors being able to be spaced apart from one another in an axial direction. The motors and couplings can in this respect extend substantially in parallel radially outwardly away from the rotating shaft. The radial extent of the overall arrangement is advantageously kept small in this respect.
In another example separating disks may be provided between at least two couplings. A mechanical separation between the couplings is thus established which allows an advantageously low-disturbance, separate functioning of the couplings.
In a further example couplings are provided which are the same and/or motors are provided which are the same or that couplings which are the same and motors which are the same are provided offset from one another at the common rotating shaft.
In this way, the inexpensive multiple use of the same components is thus advantageously possible which can furthermore be used in different numbers and in this respect without various substantial modifications to the overall arrangement. A larger range of motor arrangements having different numbers of motors can thus be provided using the same basic construction.
In another example position sensors are provided which are the same and/or that the position sensors are provided within a housing of the motor arrangement and/or that the position sensors are coupled with the outer coupling part and/or that the position sensors are differential transformers.
The integration of the position sensors in the housing and the connection of the sensors to the outer coupling parts causes an advantageously smaller mass of the arrangement with a correspondingly reduced inertia of the moving parts of the motors. The maximum required torque can thus be kept low, whereby the motor dimensions can also be kept small. The provision of the sensors of an otherwise necessary disturbance suppression apparatus is also not necessary since in the case of the disturbance or jamming of a sensor the coupling allows a further movement of the rotating shaft.
In one example the rotating shaft is supported via dual bearings.
In the case of a degradation of a bearing surface or of one or more rolling elements, the second, undegraded part of the dual bearing can continue to enable a further movement of the rotating shaft with a small frictional resistance.
Further details and advantages of the present disclosure will be shown with reference to the Figures.